Abstract
Purpose :
The current phototoxicity threshold used for domestic lighting regulation is based on the toxicity of blue light at 445 nm. The limit exposure values were calculated from data obtained in rodents and non-human primates. The other parts of the visible spectrum such as green or red wavelengths are considered non-toxic for the retina and not relevant for phototoxicity. We previously showed that the blue part of the spectrum was not the solely responsible of the phototoxicity of a white light. Moreover, commonly used white light-emitting diodes (LED) display a spectral imbalance characterized by a low proportion of red wavelengths. Here, we aim to evaluate the effect of each part of the spectrum on the retinal damage induced by white light, and to investigate the impact of the lack of red component on white light phototoxicity.
Methods :
Young male Wistar rats were exposed to lights of different wavelengths. Blue, white, green and red LED were used. Light-induced damage to the retina was evaluated by immunostaining on retina sections and quantification of proteins involved in cell death mechanisms and stress response pathways by western blot on retina samples.
Results :
Decomposition of the white light spectrum into a blue and a green part shows the implication of the green part in the phototoxicity through the induction of an inflammatory and stress response, while the blue part is responsible for the induction of a caspase-independent apoptotic pathway. The exposure to red light alone shows no impact on retinas. However, the addition of wavelengths of the red part of the spectrum mitigates the photoreceptor cell death induced by an exposure to white light alone and modifies the retinal stress response.
Conclusions :
Taken together, these results show that the phototoxicity of white light is not reduced to the phototoxicity of its blue component and is sharpened by the low proportion of red light in its spectrum, found in most of the white LED used in domestic lighting. These results highlight the importance of the spectral composition of the light on its retinal phototoxic effect.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.